Shield tunneling method

ABSTRACT

An axially slotted roof shield is supported at its front end on a tunneling machine (or shield) frame. The frame includes a fulcrum support portion inset from said shield slots. One or more fulcrum members are movably supported on said support portion. A tunnel set or the like is anchored in the tunnel rearwardly of the frame. The fulcrum member(s) is initially positioned forwardly on its support. Elongated support poles are inserted from below the shield upwardly and forwardly through the slots. The forward portions of the poles extend into or under ground ahead of the shield. Intermediate portions of the poles rest on the fulcrum member(s). The rear portions of the poles underlie the tunnel set. The fulcrum member(s) is tied to the tunnel set so that it is axially fixed during forward movement of the frame.

United States Patent Watson et al.

[ 51 Feb. 8, 1972 [54] SHIELD TUNNELING METHOD [72] Inventors: Frank George Watson, Victoria; David Burnet Sugden, Tasmania, both of Aus- 211 Appl. No.: 21,032

[30] Foreign Application Priority Data 3,407,609 10/1968 Kosogorin .161/42 3,413,811 12/1968 Giacobino ..6l/45 R X FOREIGN PATENTS OR APPLICATIONS 377,300 6/1964 Switzerland ..61/85 377,758 7/1964 Switzerland ..6l/85 Primary Examiner-Dennis L. Taylor Attorney-Graybeal, Cole & Barnard [57] ABSTRACT An axially slotted roof shield is supported at its front end on a tunneling machine (or shield) frame. The frame includes a fulcruin support portion inset from said shield slots. One or more fulcrum members are movably supported on said support portion. A tunnel set or the like is anchored in the tunnel rearwardly of the frame. The fulcrum member(s) is initially positioned forwardly on its support. Elongated support poles are inserted from below the shield upwardly and forwardly through the slots. The forward portions of the poles extend into or under ground ahead of the shield. intermediate portions of the poles rest on the fulcrum member(s). The rear portions of the poles underlie the tunnel set. The fulcrum member(s) is tied to the tunnel set so that it is axially fixed during forward movement of the frame.

4 Claims, 3 Drawing Figures SHIELD TUNNELING METHOD This invention relates to a method for tunneling through friable ground (e.g., sedimentary or soft igneous rock, decomposed rock, clay and other formations which are not entirely self-supporting), and to lining a tunnel. More particularly, it relates to an advanceable ground support system comprising a movable shield for providing ground support between the tunnel face, and the lined portion of the tunnel, and to a system of poles for providing some support forwardly of the shield.

When tunneling through friable ground by a face mining method not involving the use of a tunneling machine or a shield, it is common practice to line the tunnel up close to the face and to use the support rib(s) or tunnel set(s) nearest the tunnel face for supporting elongated ground support poles which project forwardly through or below, and provide support for, the overhead ground material forwardly of the leading tunnel set. US. Pat. No. 3,413,811, granted Dec. 3, 1968, to Pasquale Giovanni Gizaobino discloses an example of this type of system.

Heretofore it has not been possible to use tunneling machines (e.g., rotary head boring machines) in friable ground with any appreciable success. This is because the ground requires support forwardly of the machine, and known tunneling machines cannot accommodate placement of a support pole system. This is because the machine constitutes an obstruction prohibiting the placement of the poles at a flat enough angle and close enough to the tunnel diameter.

The present invention relates to the provision of a tunneling machine or shield designed to permit proper placement and proper support of a system of elongated support poles without any sacrifice in machine operation or shield use, whichever the case may be. The invention also relates to a technique of installing the elongated support members during machine or shield use. I 1

The expression elongated ground support poles is used herein to describe both spiling" (poles driven forwardly into somewhat cohesive ground) and forepoles (poles placed below noncohesive friable ground, and normally requiring the use of packing to fill up voids existing between adjacent poles and between the poles and the ground material). The term poles ismeant to describe any type of elongated member (e.g.,-pipe, l-beams). Frame includes the frame portion of a mechanical excavating machine and also the frame of a shield in which workmen are protected while they mine the face with various types of mining implements.

Other objects and advantages will become apparent from the following description which relates to a rotary head boring machine incorporating the invention.

In the accompanying drawing:

FIG. 1 is a fragmentary longitudinal vertical sectional view of the tunnel boring machine and a system of forepoles;

FIG. 2 is a fragmentary top isometric view of the machine, showing its segmented roof shield, parts of a resilient support for the shield which is anchored on a forward portion of the machine frame, and a slidable arch type forepole under support member carried by a frame portion of the machine; and

FIG. 3 is a view of a full shield to which the segmented roof shield is rigidly attached.

The invention is shown in connection with a tunnel boring machine of the general type disclosed by U.S. Pat. No. 3,232,670, granted Feb. 1, 1966, to Richard J. Robbins and Douglas F. Winberg. Certain basic parts of this machine will now be described.

A rotary cutterhead is joumaled for rotation forwardly of a cutterhead support 12, constituting a frame portion of the machine, by a large diameter bearing. The bearing includes an inner race 14 fixed to the cutterhead and an outer race 16 fixed to the cutterhead support 12. The inner race 14 is an integral part of a large diameter ring gear 18 having radially inwardly projecting teeth. Motor driven pinions (not shown) mesh with the gear 18 and serve to drive the cutterhead in its rotary motion.

Wall engaging shoes 20 are provided on the sides and at the lower portion of the machine immediately rearwardly of the cutterhead 10. These shoes are adjustable radially and slide in the tunnel as the machine advances. A number of freely and independently rotatable hardened steel disc cutters 22 are mounted in a pattern on the front face of the cutterhead 10. The cutterhead also includes gage cutters 24 at locations around its periphery, and a tricone-type center cutter 26. During tunneling the rotating cutterhead is driven forwardly into the ground material 28 at the tunnel face 30. Each cutting wheel 22 crushes the rock to form a V-shaped groove in the tunnel face 30. Each following cutter is appropriately placed so that it forms another groove in the face 30 which is radially close to the first groove. The ground material between the grooves breaks off and tends to drop. During rotation of the cutterhead it is picked up by buckets 32 located at the cutterhead periphery circumferentially between the gage cutters 24. When the buckets become inverted at the top of their path of travel, the ground material falls through a chute 34 onto a conveyor belt 36 which carries it to the rear of the machine (not shown). The conveyor belt 36 deposits the material onto a main conveyor (e.g., a train including a locomotive and muck cars riding on rails) for carrying the material out of the tunnel.

The apparatus used for moving the machine forwardly in the tunnel may be of the general type shown by US. Pat. No. 3,061,287, granted Oct. 30, 1962 to James S. Robbins, or disclosed by US. Pat. No. 3,295,892, granted Jam. 3, 1967 to Douglas F. Winberg and John Galgoozy. The conveyor 36 is supported by a main beam 38 forming a part of the main frame of the machine. The main beam 38 is interconnected between the cutterhead support 12 and the advancement structure (not shown) which trails the cutterhead assembly in the tunnel.

An access door 40 may be located in the center region of the cutterhead 10, to cover a passageway provided for gaining access to the front of the cutterhead 10. This access is needed by workmen who need to service or replace the cutters 22, and also by workmen who must pack. the support pole system, which is hereinafter described in detail. Additional access for workmen leading to the regions requiring packing" may be provided through an upper portion of the cutterhead (e.g., through a bucket 32).

The overhead ground support system of the present invention will now be described.

The illustrated embodiment includes an arcuate short shield," designated 42. It may comprise an arcuate beam 44 and a separate, axially short, panel 46 which leads the beam 44. A plurality of axially elongated shield members or teams 48 are connected at their forward ends to the panel 46, and are supported by the beam 44, and they project axially rearwardly from these short shield components at least as far back as the forwardmost permanent or temporary tunnel set 50, or an equivalent support means for the trailing portion of the shield members 48.

The shield beams 48 are circumferentially spaced apart and define between themselves a plurality of axially elongated slots 52. As will hereinafter be explained in greater detail, the slots 52 are provided primarily for accommodating elongated ground support poles or members 54.

In the embodiment being described the arcuate beam 44 is connected to the machine frame 12 by a plurality of circumferentially spaced support assemblies 56. As perhaps best shown by FIG. 2, each assembly 56 comprises a support post 58 which is rigidly connected at its base to the cutterhead support 12. An elongated support arm 60 of slight dihedral form is pivotally attached at a location between its ends to the upper end of the post 58 by a transverse pivot pin 62. A pair of pin mounting cars 64 depends downwardly from the beam 44 at each support assembly location. The forward end portion of the arm 60 is located between the cars 64 and is pivotally connected to the ears 64 by a transverse pivot pin 66. Either a fluid linear motor 68, or a resilient mounting (e.g., a spring including mounting) is interconnected between the rear end portion of the support arm 60 and the cutterhead support 12. Both mountings would permit radial in and out movement of the overhead shield structure 42-48. I

In the embodiment being described a plurality of blocks or castellations 70 project radially outwardly from the beam 44 into the slots 52. During forward movement of the tunneling machine the leading faces of the members 70 engage the trailing faces of the member 46, resulting in the comblike shield structure 46, 48 being shoved forwardly with the machine. The members 70 are narrower than the slots 52 and do not project upwardly from beam 44 beyond the upper surfaces of the members 48. Asa result, the machine can be backed up to some extent without movement of the shield structure 46, 48. As can readily be appreciated from an inspection of FIG. 2, during rearward movement of the machine the members 70 move out of engagement with the member 46 and are free to travel rearwardly through the slots 52. This capability is important because it permits the machine to be backed up a short distance (e.g., for the purpose of repairing or replacing cutters) without appreciably disturbing the overhead support at the face region.

The slotted form of the shield assembly 46, 48 provides a shield which will adequately support the ground immediately over the machine, and which is more resilient and for this reason less likely to bind when hard rock is encountered than a solid sheet shield, or a wide panel segmented shield. A disadvantage of tunneling shields of the type having a continuous or large area shield above the machine is that if only a portion of the shield binds v.on or is frictionally retained by some hard material, the machine or shield as a whole is generally held against movement. The chances of binding are materially reduced with the shield of the illustrated embodiment. If one of the relatively narrow beams 48 contact some very hard material, it usually merely bends so that the shield as a whole is not held. i

A further advantage of the slotted shield is that the presence of the slots make it possible to inspect the material immediately over the machine, and to even drill upwardly directed inspection holes if that is necessary or desirable. However, an even more important advantage is provided by such slots and their arrangement with respect to other equipment, soon to be described. They make possible the use of forepoling or spiling," or a combination of both, something that heretofore has not been practical in a shield or machine mined tunnel.

A plurality of circumferentially spaced, axially elongated beams 72 are inset radially inwardly from the shield members 48 and the slots 52. Such beams 72 are secured to the machine frame by means not shown. These beams 72 are shown to support a sliding arcuate beam 74. The arcuate beam 74 lies on, and slides along, the upper surfaces of the beams 72. The beams 72, 74 altogether constitute under supports for intermediate portions of the support poles 54.

In operation, the arcuate beam or fulcrum member 74 is initially located relatively close behind the beam 44. This is done when such location is forwardly of the last installed tunnel set 50 a distance substantially equal to the distance between adjacent tunnel sets in the tunnel. A plurality of cables or rods 76 are interconnected between the arcuate, slidable beam 74 and the fixed tunnel set 50 (FIG. 2). Next support poles 54 are installed through at least some of the slots 52. Each support pole 54 is located over the beam 74 and under the upper portion of the forward tunnel set 50. When forepoling is used, a plurality of blocks 78, or pieces of other solid material, are packed into the vertical spaces between the new set of support poles 54 and the immediately preceding set of installed forepoles, and into the cavities existing between the forward portion of the new forepoles 54 and the unsupported ground material 80 above such forward portions. An unpacked cavity 82 is shown in FIG. 1. The access through the cutterhead is normally necessary to allow personnel forwardly of the cutterhead for packing the cavities 82. This access may be provided by the passageway closed by door 40, or by some other access passageway designed in the cutterhead 10.

Following at least most of the packing, the tunneling machine is again advanced forwardly in the tunnel. During its advancement the cutterhead 10 is revolving and is cutting additional material from the tunnel face 30. The tie cables 76 maintain the arcuate beam 74 in a fixed position axially with respect to the forwardmost tunnel set 50. Hence, the support of the last installed set of forepoles 54 is not disturbed. The shield beams 48 merely slide over, and the lower support beams 72 merely slide under, the arcuate beam 74. As soon as the machine has been advanced forwardly a distance about the length of the beam 72, a new forward tunnel set 50 is assembled, a new sliding beam 74 is installed, and the procedure is repeated.

According to the present invention, an upper segment (e.g., a segment of a length about equal to one-third the circumference of the tunnel) may be used as the under support beam 74. Then, shortly before the support beams 72 are moved out from under the beam 74, the lower tunnel set segments 84 (FIG. 1) are brought into place and are assembled to the beam 74, to complete a new tunnel set. The rear portions 73 of the beams 72 are removable so that they can be removed to provide clearance space for installing a new beam 74. This may be simply done by welding end plates onto the ends of the beam parts and then bolting the parts together through these plates. In FIG. 2 the bolts are designated 75.

The various components of the advanceable overhead ground support system described above can each take several different forms. For example, the beams 44, 46 may be fixed together, or replaced by a single unitary member, or the short shield portion of the system may be the upper leading portion of a continuous ring or full shield, such as the soon to be described shield shown by FIG. 3. Or, the beam 44 and the slotted shield 46, 48 could be circumferentially divided into a plurality of independently movable sections.

The shield beams or fingers 48 defining the slots 52 could be relatively deep, relatively stiff beam members (e.g., I-beams) instead of being relatively thin and flexible. Or, a combination of flexible and rigid beams could be used.

A plurality of individual blocks or supports, one for each support pole 54, could be substituted for the arcuate under support beam 74. These supports could be designed for sliding (e.g., a solid block) or rolling (a roller) movement, or a combination of both (e.g., a transverse slidable pin supporting a rotatable roller which engages the under surface of a support pole 54).

The support beams 72 may be either rigidly fixed to the cutterhead frame or may be resiliently supported on the cutterhead frame. Also, such beams 72 may be replaced by a cylindrical segment which is also either rigid or resiliently mounted onto the cutterhead frame.

Reference is now made to FIG. 3 of the drawing. This figure shows what may be termed a full shield 86. In this form the short shield is an axially short upper forward portion 88 of the shields outer skin. The axially elongated beams 90 are again shown to be relatively thin and flexible members. In this form they are fixed to the short shield 88.

In this form the axial beams 72 are replaced by a continuous support member 92 which is a segment of a cylinder that is smaller in diameter than the outer diameter of the shield. This cylindrical segment 92 is an integral part of the shield structure 86. During use the support poles 54 are located within the axial slots 94 and the arcuate under support beam 74 or its equivalent is slidably supported on the upper surface of the cylindrical segment 92.

The shield 86 is shown to include slotted portions at each side, forming fingers 96 at the sides which are somewhat resilient. This facilitates movement of the shield along an arcuate path. The shield 86 is also shown to include a pedestal 98 onto which a cutterhead support may be secured.

Although the support system of the present invention has been shown and described in connection with tunneling machines utilizing a rotary boring head, it is to be understood that such system may be used in connection with other types of tunneling machines, or with shields employing almost any type of mining technique that is employable with a shield in friable ground.

The force system of the present invention will now be described. A movable base frame structure is located in the tunnel immediately rearwardly of the tunnel face. it is designed to transmit loadings on it to the floor and/or side walls of the tunnel, and is sufficiently strong to resist being crushed or deformed by such loads. This base frame may be either the frame of a tunneling machine or the frame portions of a tunneling shield (e.g., a cutterhead support), or some other frame assembly movable within a tunnel. A short shield is located in an upper leading position in the tunnel and is carried by the base frame. A plurality of spaced-apart, side-byside beams extend rearwardly from the short shield to the last erected tunnel set or an equivalent support structure rearwardly of the movable base frame. These beams are supported at their front ends by the short shield and at their rear ends by the tunnel set or the equivalent structure.

The tunnel sets are expanded so as to closely fit the girth of the tunnel, and are packed" where necessary, so that they transmit loads on them to the floor and sidewalls of the tunnel. The axial support beams 74 or their equivalent (e.g., the cylindrical segment type support 92) are anchored on the movable base frame and transmit their loads to the base frame. The slidable under support beam '74 or its equivalent transmits loads on it through the beam 72 to the movable base frame. The forepoles 54 rest at a point intermediate their lengths on the under support 74, which acts as a fulcrum. The rear portion of the poles 54 underlie the assembled tunnel set 50. The forward portions of the poles 54 are loaded by the ground 80 through the packing materials 78. Thus, some of the loading on the poles 54 is transmitted to the associated tunnel set 50 and the remainder to the under support beam 74, and from it to the traveling base frame by way of the beams 72 or their equivalent. Part of the loading on the shield beams 48 is carried by the forward assembled tunnel set 50 and the rest is transmitted by the short shield 42 through its support structure to the traveling base frame. Once a new tunnel set has replaced an under support beam 74, the only change in the force system is that the particular forces once carried by the traveling base frame through such under support beam 74 is now being carried by the new tunnel set 50.

The invention should be clear from the foregoing description. No limitations are to be implied from such description, and its is our intention that the language of the following claims should be given the broadest interpretation which the terminology use permits.

What is claimed is:

1. A method of tunneling through friable ground, comprising: locating a longitudinally slotted roof shield contiguously below the tunnel roof; supporting said slotted roof shield on a frame; moving said frame and slotted roof shield forwardly together in the tunnel while mining the tunnel face; installing ground support poles from below said shield, forwardly and upwardly through said slots into a supporting position for ground forwardly of the shield; firmly anchoring the rear portions of the poles for supporting the poles in cantilever fashion; then advancing the frame and slotted shield while doing further mining; and then installing further support poles through said slots, as before.

2. The method of claim 1, further comprising locating fulcrum means on a forward part of a fulcrum support portion of the frame having axial length, resting an intermediate portion of the elongated support poles on the fulcrum means, holding the rear portions of said poles against movement, and moving the frame forwardly, including the fulcrum support portion, while holding the fulcrum means against axial movement.

3. The method of claim 2, further comprising using an upper portion of a tunnel set as the fulcrum means, and securing the remaining portion of such set thereto to complete the next tunnel set for the tunnel lining once the frame has traveled a predetermined distance forwardly.

4. The method of claim 3, further comprising moving the rear portion of the fulcrum support portion to provide an avenue for placing a new fulcrum means onto the support portion. 

1. A method of tunneling through friable ground, comprising: locating a longitudinally slotted roof shield contiguously below the tunnel roof; supporting said slotted roof shield on a frame; moving said frame and slotted roof shield forwardly together in the tunnel while mining the tunnel face; installing ground support poles from below said shield, forwardly and upwardly through said slots into a supporting position for ground forwardly of the shield; firmly anchoring the rear portions of the poles for supporting the poles in cantilever fashion; then advancing the frame and slotted shield while doing further mining; and then installing further support poles through said slots, as before.
 2. The method of claim 1, further comprising locating fulcrum means on a forward part of a fulcrum support portion of the frame having axial length, resting an intermediate portion of the elongated support poles on the fulcrum means, holding the rear portions of said poles against movement, and moving the frame forwardly, including the fulcrum support portion, while holding the fulcrum means against axial movement.
 3. The method of claim 2, further comprising using an upper portion of a tunnel set as the fulcrum means, and securing the remaining portion of such set thereto to complete the next tunnel set for the tunnel lining once the frame has traveled a predetermined distance forwardly.
 4. The method of claim 3, further comprising moving the rear portion of the fulcrum support portion to provide an avenue for placing a new fulcrum means onto the support portion. 